Seven Ukrainian soldiers were killed in a rebel ambush in the restive east of the country on Tuesday, the defence ministry and security sources said, in one of the deadliest days for the military since the start of an uprising in the region against Kiev's rule.
A military convoy was attacked near a river in a village between the rebel bastions of Slavyansk and Kramatorsk by a group of about 30 men who fired heavy weapons including grenade launchers, the ministry said.
The troops responded, triggering "prolonged clashes" that left six soldiers dead and eight wounded, the ministry said.
A spokeswoman for the Ukrainian security services said later the death toll had risen to seven.
Another nine Ukrainian soldiers have been killed since Kiev launched a so-called "anti-terrorist" operation in the east in mid-April, a defence ministry official said.
It is not known how many police or other members of the security forces have been killed.